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W. B. GRIFPI-THS.

DEVIGB POP. LAYING OPF GBOMBTRIG FIGURES.

Patented June '7, 1887.

(No Modl.)

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BY Ywmnbvqu/f mmf www square or other polygon.

To all whom, it may concern:

UNITED STATES VALTER B. GRIFFI'IHS,

PATENT OFFICE.

OF NEYV YORK, N. Y.

DEVICE FOR LAYING OFF GEOMETRIC FGURES.

SPECIFICATION forming part of Letters Patent No. 364,508, dated June 7, 1887.

Application filed February 2G, 18S?.

Be it known that I, WALTER B. Gnirrrrns, a. subject of the Queen ot' Great Britain, residing at New York, in the county and State of New York, have invented new and useful Improvements in Devices for Laying Off Geometric Figures, of which the following is a specication.

My invention consists in a device for laying off geometricgures--such as circles and polygens-and also for the production of various ornamental designs. The said device being complete in itself, the use of dividers and other drawing-instruments can be dispensed with. It isintended as an aid in drawing, and also for the instruction of children in the prellnnnary steps of drawing.

rIhe novel features of my invention are fully pointed out in the following spcclication and claim, and illustrated in the accompanying drawings, in which Figure l represents a face view of a device embodying my invention. Fig. 2 is a section thereof in the plane x x, Fig. I. Fig. 3 is a face view of a design produced with the aid of the said device.

Similar letters indicate corresponding parts.

In the drawings, the letter A designates a polygonal disk, which can be in the form of a triangle, preferably equilateral, as shown in this example, or it may be in the form of a Withinthe body of thedisk is a hole or perforation, B, which is sufficiently large to receive a pin, about which, as a center, the disk can be rotated. With this hole or perforation B as a center is cut a protractor, D, and the material forming one quadrant of the protractor is 'eut awayv to form an opening, E, in order that the de! grees can be transferred upon the sheetto be drawn upon. In the outer circle of the protractor D (shown by dotted lines in Fig. l) are arranged a series of equidistant. perforationsl or holes, d, through which the pencilpoint can pass. By inserting the pencil-point through any one of said holes and rotating the disk .a circle, as D', Fig. 3, of a determined diameter can be drawn, which can be divided into any number of equal parts by passing the pencil-point through selected equidistant holes or perforations cl. The holes or perforations Serial No. 228.986. (No model.)

d at the 0, 90", and 270O points also serve to form an exact square, as F in Fig. 3-as, for instance, by .marking the said three points on the paper, as at d, Fig. 3, and then rotating the disk A through one quadranththat is, until the perforation at the Oo point reaches the 90o pointe-the fourth point, d, Fig. 3, of

vthe square can be marked off. The sides of the square are drawn in by the use of any of the sides a b c of the disk A as a rule.

To draw any number of concentric circles from the center B, a row of holes or perfora tions, `g, is provided, which are tangent to an are described from the center B, and caneX- tend parallel to one of the sides of the diskfor instance, to the base l1 thereof. By means of the row of perforations circles of any size within limits can be drawn, also concentric circles arranged at equal distance apart. These perforations g can be used also for dividing aline into an equal number of parts by passing the pencil-point through eqnidistant perforations.

To draw polygonal figures, I mark out upon the sides c and c of the disk lengths F, corresponding to the chords subtended by deiinite varying arcs of the circle marked by the holes or perforations (l. By first drawing the circle any polygon can be laid out by applying the said lengths F to the circle, making the points, and then drawing in the chords, as F in Fig. 3. The base b of its triangular disk is `provided with a scale, as G, Fig. 1, which is convenient for measuring purposes and for dividing lines into equal parts. In the body of the disk openings are cut to formornamental designs, such as H, I, J, and K, and also circles of varying sizes, such as Land M. By running the point of a pencil along the edges of any one of these designs the same can be copied on paper. In Fig. 3 the design H has been copied several times, said designs being arranged about a common center. This is accomplished by turning the disk through a definite angleafter each time that the design is copied-for instance, through an angle of ninety degrees.

The design shown in Fig. 3 is completed by applying the scale G to divide the square into equal parts and then connecting the intersections ofthe dividing-lines, as shown.

ICO

VhatI claim as new, and desire to secure litestinony whereof I have hereunto set by Letters Patent, is my hand and seal iu the presence of two Sub- A polygonal disk containing a center and a scribng Witnesses. series of perforatons arraugedin an are about WALTER B. GRIFFITHS. [L 5.] 5 said center, invcombinabiou with subtendng Vtnesses:

chords marked on a side or sidesA of the disk, A. FABER DU FAUR, Jr.,-

substantinl] y as shown and described. E. F. KASTENI-IUBER. 

